As already mentioned in DE 197 40 550, a programmable logic controller and a programming unit for creating a control program for a programmable logic controller of this kind are disclosed as automation devices in the Siemens Catalog ST 70, 1996 edition, Sections 3, 4 and 8. Important components of this programmable logic controller are modules for central tasks (CPU units) as well as signal, function and communication modules. During control operation, the CPU unit of the programmable logic controller cyclically executes a control program which a programmer creates using a programming unit provided with a software tool and which is designed to solve an automation task. During cyclical processing, the CPU first reads the signal statuses at all the physical process inputs and generates a process input image. Execution of the control program continues step by step, taking internal counters, flags and times into account, and finally the CPU unit stores the calculated signal statuses in the process output image from which these signal statuses are fed to the physical process outputs. A control program usually comprises software function blocks which enable the signal and/or function and/or communication modules to be operated. One of these function modules in the form of an NC control module can be used to control the technological sequence of motions of a production machine. For this purpose the CPU unit, which usually implements process control functionalities, transmits parameters to this NC control module, e.g. parameters in the form of start/stop coordinates of the production machine's drive axles to be controlled. In addition, the CPU unit selects process programs executable on the NC control module which are executed by a processor of the NC control module for controlling the sequence of motions of a production machine.